Numerical simulation of radial duel-stage nozzle vortex cooling at the leading edge of a gas turbine blade

Thermal failure is one of the major challenges faced by the leading edge of gas turbines, which significantly affects the improvement of their efficiency. The vortex cooling technique has become a promising solution to address this issue. Radial duel-stage nozzle vortex cooling (RDNVC) model, featured with a vortex tube and two sets of nozzles, is proposed based on the radial single-stage nozzle vortex cooling (RSNVC) configuration. This novel structure aims to intensify turbulence within the cooling fluid at the nozzle inlets, thereby improving heat transfer at the leading edge. The model improves turbulence in the cooling fluid, promoting better heat transfer at the leading edge. Numerical simulations with the SST k-omega turbulence model were performed to analyze heat transfer and flow characteristics at varying Reynolds numbers (Re). The results show that the non-uniform inlet velocity in RDNVC increases turbulence and vorticity inside the vortex tube, leading to improved heat transfer. At the same cooling airflow rate, RDNVC increased the global average Nusselt number by 23.56% compared to RSNVC. Nu increases with Re. Among the three models, RDNVC(6-2) (nozzle heights of 6 mm and 2 mm) showed the best thermal performance, followed by RDNVC(2-6), while RSNVC had the lowest thermal performance. For the same pressure drop, RDNVC(2-6) achieved an 8.42% improvement in heat transfer efficiency over RSNVC. Based on Re and geometry parameters, the empirical correlation for the global average Nusselt number of RDNVC is also proposed.